Bronchial and cutaneous responses in atopic dermatitis patients after allergen inhalation challenge

The Role of Inhalant Allergens on the Clinical Manifestations of Atopic Dermatitis

BACKGROUND

Inhalant allergens provide a source of environmental factors that contribute to the development of clinical symptoms in patients with atopic dermatitis (AD).

OBJECTIVE

To review the relationship between inhalant allergens and AD.

METHODS

A literature review was conducted using three databases: PubMed/MEDLINE, ClinicalKey, and Web of Science. Search terms, including "atopic dermatitis," "atopic eczema," and "eczema," were used in combination with "inhalant allergen," "inhaled allergen," and "aeroallergen" to identify relevant published manuscripts that highlight the relationship between AD and exposures to inhalant allergens.

RESULTS

Fifteen articles were suitable for review. The studies included in the review investigated the effect of inhalant allergens on the clinical manifestations of AD through bronchial provocation, direct skin contact, and allergen sensitization.

CONCLUSION

There is a significant relationship between exposures to inhalant allergens and AD. Inhalant allergens may aggravate AD symptoms by either bronchial provocation or direct skin contact. Sensitization of inhalant allergens, mainly house dust mites, follows a specific age-related pattern.

Beyond the Skin: Reduced Lung Function Associated With Atopic Dermatitis in Infants

BACKGROUND

Very few studies have examined lung function parameters using tidal breath analysis (TBA) in atopic dermatitis (AD) with its high potential for progression to asthma.

OBJECTIVE

To measure lung functions using TBA in infants with AD and in healthy controls (HCs), and to investigate the effects of disease severity, food sensitivity, and history of recurrent wheezing on TBA parameters in infants with AD.

METHODS

Two hundred thirty infants were included in this prospective cross-sectional study, including an AD group (n = 150) and an HC group (n = 80). Food sensitivity was assessed by means of food-specific IgE or the skin prick test. The severity of the disease was evaluated using the SCORing Atopic Dermatitis. Lung function was assessed using TBA.

RESULTS

The following TBA parameters were significantly lower in the AD group than in the HC group (P < .05): time to peak tidal expiratory flow, exhaled volume to peak tidal expiratory flow, ratio of time to peak tidal expiratory flow to expiratory time, ratio of exhaled volume to peak tidal expiratory flow to total expiratory volume, expiratory flow when 25% of tidal volume remains in the lungs, respiratory rate, and minute ventilation. No difference was observed in the AD group when TBA parameters were compared according to disease severity, food sensitivity, and history of recurrent wheezing (P > .05). The receiver-operating characteristic curve demonstrated by the ratio of time to peak tidal expiratory flow to expiratory time yielded an area under the curve of 0.826 (CI, 0.772-0.879), with a cutoff value of 31.65 or higher in differentiating AD, with a sensitivity of 78.7% and a specificity of 77.5%.

CONCLUSIONS

TBA curves can be a useful tool for demonstrating expiratory airway obstruction in AD and for providing objective information for the clinician. Bronchial obstruction was detected in young children with AD irrespective of the severity of the disease, food sensitivity, and history of recurrent wheezing.

Temperature-controlled laminar airflow (TLA) device in the treatment of children with severe atopic eczema: Open-label, proof-of-concept study

BACKGROUND

Children with severe, persistent atopic eczema (AE) have limited treatment options, often requiring systemic immunosuppression.

OBJECTIVE

To evaluate the effect of the temperature-controlled laminar airflow (TLA) treatment in children/adolescents with severe AE.

METHODS

We recruited 15 children aged 2-16 years with long-standing, severe AE and sensitization to ≥1 perennial inhalant allergen. Run-in period of 6-10 weeks (3 visits) was followed by 12-month treatment with overnight TLA (Airsonett^® , Sweden). The primary outcome was eczema severity (SCORAD-Index and Investigator Global Assessment-IGA). Secondary outcomes included child/family dermatology quality of life and family impact questionnaires (CDQLI, FDQLI, DFI), patient-oriented eczema measure (POEM), medication requirements and healthcare contacts. The study is registered as ISRCTN65865773.

RESULTS

There was a significant reduction in AE severity ascertained by SCORAD and IGA during the 12-month intervention period (P < .001). SCORAD was reduced from a median of 34.9 [interquartile range 28.75-45.15] at Baseline to 17.2 [12.95-32.3] at the final visit, and IGA improved significantly from 4 [3-4] to 2 [1-3]. We observed a significant improvement in FDQLI (16.0 [12.25-19.0] to 12 [8-18], P = .023) and DFI (P = .011), but not CDQLI or POEM. Compared to 6-month period prior to enrolment, there was a significant reduction at six months after the start of the intervention in potent topical corticosteroids (P = .033). The exploratory cluster analysis revealed two strongly divergent patterns of response, with 9 patients classified as responders, and 6 as non-responders.

CONCLUSION AND CLINICAL RELEVANCE

Addition of TLA device to standard pharmacological treatment may be an effective add-on to the management of difficult-to-control AE.

Exacerbation of atopic dermatitis on grass pollen exposure in an environmental challenge chamber

BACKGROUND

It has frequently been speculated that pruritus and skin lesions develop after topical exposure to aeroallergens in sensitized patients with atopic dermatitis (AD).

OBJECTIVE

We sought to study cutaneous reactions to grass pollen in adult patients with AD with accompanying clear IgE sensitization to grass allergen in an environmental challenge chamber using a monocenter, double-blind, placebo-controlled study design.

METHODS

Subjects were challenged on 2 consecutive days with either 4000 pollen grains/m(3) of Dactylis glomerata pollen or clean air. The severity of AD was assessed at each study visit up to 5 days after challenge by (objective) scoring of AD (SCORAD). Additionally, air-exposed and non-air-exposed skin areas were each scored using local SCORAD scoring and investigator global assessments. Levels of a series of serum cytokines and chemokines were determined by using a Luminex-based immunoassay. The primary end point of the study was the change in objective SCORAD scores between prechallenge and postchallenge values.

RESULTS

Exposure to grass pollen induced a significant worsening of AD. A pronounced eczema flare-up of air-exposed rather than covered skin areas occurred. In grass pollen-exposed subjects a significantly higher increase in CCL17, CCL22, and IL-4 serum levels was observed.

CONCLUSIONS

This study demonstrates that controlled exposure to airborne allergens of patients with a so-called extrinsic IgE-mediated form of AD induced a worsening of cutaneous symptoms.

Evaluation of the adult patient with atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a large impact on quality of life of the patients and their families. In most cases, the diagnosis of AD can easily be made based on (family) history and clinical examination. If necessary, a practical set of diagnostic criteria such as the UK diagnostic criteria can be used. During the diagnostic phase, it is important to pay attention to atopic comorbidity, such as allergic airway disease (allergic asthma and/or rhinitis), allergic eye disease (atopic (kerato) conjunctivitis) and immediate-type food allergy. This will not have direct consequences for the treatment of AD, but may be important for the overall well-being of the patient. Psychological factors, such as family circumstances, work/school performance and lifestyle factors should also be explored. Severity scoring using properly validated scoring lists may not be necessary for the diagnosis, however, is recommended for monitoring therapy. Simple scoring systems, such as TIS and IGA are easy to perform in daily practice. Several flare factors in AD, such as exposure to irritants or UV light, can be identified by history and clinical examination: in individual cases, additional diagnostic tests may sometimes be useful to confirm clinical suspicion. There is only limited evidence that allergen exposure to aeroallergens and/or food allergens influences AD severity. Therefore, routine allergen testing is not necessary for diagnosis and treatment of AD. The decision to perform allergen tests mainly depends on atopic comorbidity.

Halting the allergic march

The prevalence of childhood allergic diseases, such as allergic asthma, allergic rhinitis, and atopic dermatitis, has increased exponentially. In Singapore, the prevalence of asthma at all ages exceeds 20%, and around 50% of Singaporean children show features of an underlying allergy. The exact environmental causes for the increase of allergic diseases have not yet been identified, but most researchers agree that a decreased bacterial load in young children may be one of the reasons for the increase. However, the causes of allergy are multiple, and the development of an allergic disease is the result of complex interactions between genetic constitution and environmental factors. In this review article, different aspects of allergic sensitization are covered, including prenatal and postnatal sensitization. The phenomenon of the "allergic march" (switching from one clinical expression of allergy to another) and its underlying mechanisms are discussed. The last part of this review article is on prevention and treatment of allergic diseases, including the role of bacterial products (probiotics, prebiotics, and synbiotics) and the role of immunotherapy, including sublingual immunotherapy.

Effects of ambient fine particles on pulmonary function in children with mild atopic dermatitis

The effects of particulate pollutants on lung function in children with atopic dermatitis (AD) remain to be determined. The authors investigated the short-term effects of ambient particles on peak expiratory flow rate (PEFR) in 84 children with and without AD. Daily particulates less than 10, 2.5, and 1 μm (PM(10), PM(2.5), and PM(1)) and number concentrations of submicron particles were measured. The authors observed elevated levels of PM(10), PM(2.5), and PM(1), and accumulation-mode particles were associated with decreased PEFR in children with AD. The PEFR decrements were -2.89 L/min (95% confidence interval [CI], -4.93 to -0.89) for an interquartile-range increase of previous-day PM(10), -2.79 L/min (95% CI, -4.89 to -0.69) for PM(2.5), and -2.71 L/min (95% CI, -4.81 to -0.61) for PM(1). These results suggest that ambient fine particles may affect the pulmonary function in children with AD. The respiratory health of children with atopic skin disorders renders them more vulnerable to ambient particles than healthy subjects.

[House dust mites and their allergens]

The taxonomy, anatomy, life cycle and ecology of Pyroglyphidae mites and storage mites (Acaridae, Glycyphagidae, B. tropicalis) are described. Pyroglyphidae and storage mites have similar morphologies: they are octopods, with characteristic gnathosoma and sensory hairs. Salivary glands and the mid gut produce most of the allergens excreted, which are enzymatic proteins. Biological cycles and development are similar, although fecundity is superior in storage mites compared to the Pyroglyphides. Relative humidity is the main parameter, which regulates mite development, with a higher degree of temperature and humidity required for storage mites. Bedding is the ecological niche of Pyroglyphidae, which feed on human skin. Moulds and food products are the storage mite biotope from which they spread in the dwelling. Initially considered as rural mites, storage mites are also present in urban dwellings. B. tropicalis, in tropical regions is a true domestic mite. Because of this, it is justified to denominate Pyroglyphidae "house dust mites" and storage mites "domestic mites". In addition to the respiratory allergic symptoms, the storage mites can also cause occupational contact dermatoses.

Acute urticaria[corrected]-like lesions in allergen-unexposed cutaneous tissues in a mouse model of late allergic rhinitis

The mechanisms of distant manifestation after a local allergic reaction are largely unknown. This study examined the development of cutaneous lesions in a mouse model of late allergic rhinitis (LAR). BALB/c mice were sensitized by ovalbumin (OVA) intraperitoneally two times (on days 0 and 10) and challenged by OVA intranasally on day 14. Four days after OVA challenge, nasal and cutaneous lesions including helper T (Th) responses, expression of adhesion molecules and presence of OVA and IgE were examined, and compared with unsensitized and unchallenged (control) mice. Compared with the control group, the LAR group developed LAR characterized by infiltration of lymphocytes and eosinophils, increased IgE values and increased productions of IL-4 and IL-5, but not IFN-gamma. A dominant infiltration of eosinophils and increase in mast cells, attachment of eosinophils to endothelium, intense expression of VCAM-1 on endothelium in venules and VLA-4 expression on eosinophils and mast cells were recognized in the cutaneous tissues. There were no differences in the expression of ICAM-1 on vascular endothelium and LFA-1 on infiltrated leucocytes between the two groups. CLA expression on lymphocytes was not detected, and the binding of OVA and IgE on mast cells and eosinophils was found in the cutaneous lesions in the LAR group, but not in the control group. This study suggests that acute urticaria[corrected]-like lesions in OVA-unexposed cutaneous tissues may be induced by immediate allergic reaction due to the systemic development of Th2-type response in a mouse model of LAR.

Time for a paradigm shift in asthma treatment: from relieving bronchospasm to controlling systemic inflammation

Inflammation is a key pathology in asthma. In the central airways local inflammation leads to irreversible remodeling and airway dysfunction. Complex inflammatory changes also occur in the nose, sinuses, and small airways. In particular, rhinitis and asthma are linked by a common pathogenic process with common inflammatory cells, mediators, and cytokines. Cross-communication between the airways and bone marrow through inflammatory mediators in the circulation leads to systemic propagation of airway inflammation. Treatment of asthma has traditionally focused on relieving bronchospasm with beta(2)-agonists, which do not affect inflammation. Treatment of eosinophilic inflammation in the central airways with inhaled corticosteroids reduces local inflammation and improves pulmonary function but does not improve the systemic manifestations of asthma. If asthma is a systemic disease, the underlying systemic pathology should be targeted by identifying common disease mediators, mechanisms, or both that are triggered only during active disease. Of currently available therapies, leukotriene receptor antagonists block the action of cysteinyl leukotrienes and thus improve both asthma and rhinitis and other conditions systemically linked with asthma. Other potential treatments include receptor-blocking molecules and synthesis inhibitors related to eicosanoid inflammation. Treatment of asthma as a systemic disease requires clinical trials that evaluate the effects of new treatments on both lung function and the wider systemic pathology.

Atopy Patch Test Reactions to House Dust Mites in Patients with Scabies

It is well known that the house dust and the scabies mites are related phylogenetically. We therefore performed atopy patch tests with house dust mite antigens (Dermatophagoides pteronyssinus (Dp) and/or Dermatophagoides farinae (Df)) in scabies patients without atopy and healthy controls. We studied 25 men with active scabies and 25 healthy controls. Skin prick tests with standardized house dust mite extract were performed for all patients and controls. An intradermal test procedure was carried out in skin prick test-negative patients, and for controls showing positive atopy patch test to Dp and/or Df. While atopy patch tests were performed directly in all healthy controls, patients with scabies were first treated and on the next day, atopy patch tests were performed. Twenty-two of 25 patients with scabies (88%) had skin prick test and/or intradermal test positivity against house dust mites, whereas 17/25 patients (68%) had atopy patch test positivity against house dust mites (Dp and/or Df). There was no statistically significant difference between skin prick test and/or intradermal test positivity and atopy patch test positivity in a regression analysis (p=0.222). The only statistically significant correlation was between atopy patch test positivity and the extent of scabies involvement (p<0.05). Only few of the healthy controls had positive tests. In this study, we have shown that a positive atopy patch test to house dust mite antigens is not specific for patients with atopic dermatitis, but also occurs in scabies patients without a history of atopic dermatitis.

Immune dysregulation in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease in humans and dogs with comparable clinical features. Comparative studies of immunological events in the pathogenesis of AD may contribute to understanding of the disease in dogs and to development and evaluation of immunomodulatory strategies of relevance to both species.Both allergen-specific as well as non-specific mechanisms contribute to the disease development. AD skin lesions are proposed to be initiated by activation of allergen-specific Th2-type cells, potentially influenced by local cutaneous factors. In the chronic stage of skin lesions reactivity may change into a Th1-type, e.g. driven by eosinophil derived IL-12. Analyses of these processes in course of time were performed in both spontaneous as well as in experimentally induced lesions (i.e. atopy patch test (APT) lesions). In the present paper, the immunological events as reported for human and canine AD are summarized and compared.

Effect of mattress encasings on atopic dermatitis outcome measures in a double-blind, placebo-controlled study: the Dutch mite avoidance study

BACKGROUND

House dust mite (HDM) allergen might induce and maintain atopic dermatitis (AD). Reduction of allergen load by applying encasings might improve the clinical symptoms of AD.

OBJECTIVE

We sought to investigate, in a randomized, double-blind, placebo-controlled study, whether reducing HDM allergen levels by using mattress, duvet, and pillow encasings for 12 months will result in improvement in AD symptoms.

METHODS

Patients with AD (8-50 years old and allergic to HDM), having a Leicester sign score (a dermatitis score) of at least 1% extent and a severity score of 6 points or greater, were randomly allocated to an active (n = 45) or a placebo allergen-avoidance group (n = 41). Avoidance measures consisted of applying HDM-impermeable encasings for mattresses, pillows, and duvets for the active treatment group and cotton encasings for the placebo group. Effect on allergen concentrations (Der p 1 and Der p 1 plus Der f 1), Leicester sign score extent and severity, visual analogue scale scores for itching and sleeplessness, intradermal test results, atopy patch test results, total serum IgE levels, anti-Der p 1-specific IgE levels, and total blood eosinophil counts were studied.

RESULTS

The active encasings reduced the Der p 1 allergen concentration in the mattress after 12 months with a factor 2.1 (P =.007) and the Der p 1 plus Der f 1 allergen concentration with a factor of 2.5 (P =.005); no significant change in allergen concentrations in mattresses was seen in the placebo group. Although the decrease in allergen load was significant, no differences in treatment-induced changes were seen between the placebo and active groups.

CONCLUSIONS

Use of HDM-impermeable encasings resulted in a significant decrease in Der p 1 and Der p 1 plus Der f 1 allergen concentrations. However, this reduction in allergen load did not result in significant changes in clinical parameters between the groups. Reduction of allergens in other environments (work, school, and outdoors) might be equally important in improving symptoms of AD.

Immunotherapy in atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory disease involving the skin and often other organs and systems, mainly respiratory. A definitive general consensus on the AD pathogenesis has not yet been established, however several lines of evidence suggest that T-cells play a crucial role in priming AD early-stage lesions. Main topics involved in the disease pathogenesis have been reviewed, which considered the concept of local and systemic haemopoietic events as important contributors to allergic inflammation, a concept now achieving great acceptance. The recently recognised atopic nature of the skin inflammation in AD has raised increasing interest for treatment with allergen-specific immunotherapy. However, we only found eight studies using specific immunotherapy (SIT) in AD, two double-blind, placebo-controlled (DBPC) and six observational. One controlled and five observational reported favourable outcomes. The one unique study providing negative results was flawed by the ineffective oral route of extract administration. Despite being encouraging, the reported results do not allow definitive conclusions based on meta-analytic techniques because the amount and quality of information in the literature is not sufficient. The highly promising sub-lingual immunotherapy (SLIT) is discussed with its potential capability of controlling not only the skin lesion severity but also its capability of preventing the development of atopic dermatitis into asthma.

Clinical and immunologic variables in skin of patients with atopic eczema and either positive or negative atopy patch test reactions

BACKGROUND

Epicutaneous application of aeroallergens induces a positive atopy patch test (APT) response in about 50% of patients with atopic eczema (AE) and sensitization for these allergens.

OBJECTIVE

To elucidate the mechanisms determining the outcome of the APT, the following questions were addressed. Are there differences in clinical features between patients with AE who have positive versus negative APT responses? Is a macroscopically negative APT response also histologically negative, and if so, are there differences in clinically noninvolved skin between the two groups regarding (1) the sensitivity toward an irritant, (2) the composition of cellular infiltrate, (3) the presence of aeroallergen-specific T cells, and (4) the number of IgE(+) cells?

METHODS

Punch biopsy specimens from both house dust mite patch tested and the clinically noninvolved skin of patients with AE who have positive APT responses (n = 10) and negative APT responses (n = 10) and those from the normal skin of atopic individuals without AE (n = 10) and nonatopic volunteers (n = 10) were analyzed by using immunohistochemistry with mAbs against eosinophil cationic protein, IgE, the high-affinity receptor for IgE, and CD3 and CD25 mAbs. Furthermore, T-cell lines were propagated from noninvolved skin of all patient and control groups. The T-cell lines were tested for house dust mite specificity.

RESULTS

Negative APT sites were immunohistochemically similar to clinically noninvolved AE skin. There were no significant differences between patients with AE who had positive and negative APT results regarding either clinical features, the composition of cellular infiltrate, or the presence of allergen-specific T cells in clinically noninvolved skin. However, differences were observed regarding the presence of IgE on epidermal CD1a(+) cells.

CONCLUSION

Our results indicate that a positive APT reaction requires the presence of epidermal IgE(+) CD1a(+) cells in clinically noninvolved skin, but that also other, as yet unknown, discriminatory factors are involved.